Microscopy systems that measure interferometric phase are known. For example, one known microscopy system measures interferometric phase by illuminating an extended surface of an object with an external light source. Light reflected from the sample interferes with a reference beam in a beam splitter. The interfered beam is imaged onto a detector. The optical path difference between the reference beam and the sample beam can modulate the amplitude of the output interfered beam and provide a measure of an object height. Also known are microscopy systems that interfere two beams from a sample via opposing objectives to measure only one interfered output beam.